mstPrims.c

#include <stdio.h> 
#include <limits.h> 
#include<stdbool.h> 
#define V 5 
int minKey(int key[], bool mstSet[]) 
{ 
	int v;	
	int min = INT_MAX, min_index; 
	for (v = 0; v < V; v++) 
    	if (mstSet[v] == false && key[v] < min) 
        	min = key[v], min_index = v; 
	return min_index; 
} 
int printMST(int parent[], int n, int graph[V][V]) 
{ 
	int i;
	printf("Edge \tWeight\n"); 
	for (i = 1; i < V; i++) 
    	printf("%d - %d \t%d \n", parent[i], i, graph[i][parent[i]]); 
} 
void primMST(int graph[V][V]) 
{ 
	int parent[V];  
    int key[V];  
    bool mstSet[V];  
    int i;
    for (i = 0; i < V; i++) 
        key[i] = INT_MAX, mstSet[i] = false; 
    key[0] = 0;      
    parent[0] = -1; // First node is always root of MST  
  	int count;
  	int u,v;
    for (count = 0; count < V-1; count++) 
    { 
        u = minKey(key, mstSet); 
        mstSet[u] = true; 
        for (v = 0; v < V; v++) 
        if (graph[u][v] && mstSet[v] == false && graph[u][v]<key[v]) 
            parent[v] = u, key[v] = graph[u][v]; 
    }
    printMST(parent, V, graph); 
}
int main() 
{ 
/* Let us create the following graph 
        2 3 
    (0)--(1)--(2) 
    | / \ | 
    6| 8/ \5 |7 
    | /     \ | 
    (3)-------(4) 
            9         */
	int graph[V][V] = {{0, 2, 0, 6, 0}, 
                    {2, 0, 3, 8, 5}, 
                    {0, 3, 0, 0, 7}, 
                    {6, 8, 0, 0, 9}, 
                    {0, 5, 7, 9, 0}}; 
    primMST(graph); 
    return 0; 
}